The present invention relates to an aqueous emulsion of a tertiary butyl hydroperoxide containing a protective colloid. An emulsion of the same kind is disclosed in U.S. Pat. No. 3,061,554. The emulsion described in Example 3 of said patent specification contains polyvinyl alcohol as protective colloid and a hydrogenated tallow amide as surface active agent. After one month this emulsion was found to phase-separate. Transporting these unstable emulsions in large quantities is not without explosion hazards. For there is the change then of local concentration of the hydroperoxide as a result of phase separation and the ensuing risk of autocatalytic decomposition.
Tertiary butyl hydroperoxide is therefore marketed as a mixture saturated with water or di-tertiary butyl peroxide. Such mixtures contain 70 to 80% by weight of tertiary butyl hydroperoxide and 20 to 30% by weight of water or di-tertiary butyl peroxide. Although these formulations are considered relatively safe, the explosion hazard during storage and transport must still be reckoned with because of the relatively high peroxide content of these mixtures. Another possibility consists in preparing aqueous solutions containing up to about 18% by weight of tertiary butyl hydroperoxide. Because of their low peroxide content, however, such solutions can hardly be considered attractive from an economical point of view, particularly in the case of transporting and storing large quantities.
There is consequently a need for stable aqueous formulations containing 20 to 70% by weight of tertiary butyl hydroperoxide. Intensively mixing the two components, optionally in the presence of one or more surface active agents, merely results in unstable formulations. For when at rest, these compositions were found to rapidly phase-separate into two layers, the upper one consisting of tertiary butyl hydroperoxide (about 70%) saturated with water and the lower one of water saturated with tertiary butyl hydroperoxide (about 20%). Also found to be unstable were formulations to which as protective colloid there had been added carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, carboxyvinyl polymer, xanthan gum, gelatin, starch or agar.
Tertiary butyl hydroperoxide is used for the preparation of numerous other peroxy compounds, such as tertiary butyl perbenzoate, tertiary butyl peroxyacetate and tertiary butyl peroxypivalate. Tertiary butyl peroxypivalate is also used as initiator in the polymerization of acrylates, in preparation of acrylonitrile butadiene-styrene terpolymers, polystyrene and copolymers of styrene and butadiene.
It should be added that U.S. Pat. No. 3,061,554 describes stable, aqueous pinane hydroperoxide emulsions. Moreover, U.S. Pat. No. 3,825,509 describes stable, aqueous hydroperoxide emulsions in which 1-5% by weight of polyvinyl alcohol and 1-6% by weight of polyoxyethylene sorbitan monolaurate are incorporated. Such a stabilizing system, however, is unsuitable for preparing stable emulsions of tertiary butyl hydroperoxide. Frozen emulsions of certain organic peroxides in concentrations of 30-70% peroxide stable to freeze--thaw cycles are described in U.S. Pat. No. 3,988,261. However, the disclosure does not relate to hydroperoxides, let alone tertiary butyl hydroperoxide.